Figure
1. Area affected by the July 4-5, 1980 derecho event (outlined in blue). Curved
dark purple lines represent the approximate locations of the gust front
at three hourly intervals. The "x" symbols circled in purple represent
deaths, and the "black dots" denote personal injuries directly
attributable to derecho winds. The flag symbols denote measured wind gusts,
with the direction of the wind being from the flag end toward the lower end of the
staff. Maximum wind gusts (red numbers) in mph. (From Johns and Hirt
1987)

A bowing
line of thunderstorms producing a derecho formed just east of Omaha, Nebraska
(NE) around 10 p.m. CDT (03 UTC) on Friday evening, July 4th, 1980. The storm
front rushed east at a speed of 55 to 60 mph, reaching eastern Indiana
(IN) and northwest Ohio (OH) by 8 a.m. EDT (12 UTC) Saturday, July 5th, and the
mid Atlantic coast by early evening on the 5th. Measured
wind gusts exceeded 80 mph at several points along the storm's track. Six
people were killed (shown as "x"s circled in purple in
Figure 1), and 67 were injured (shown as dots in Figure 1) by the derecho's winds.

There
are two points worth noting about this derecho:

(1) Although
the measured wind gusts (Figure 1) do not represent every point
affected, they do show how the maximum gust speeds can vary considerably along
the path of a derecho. In this case there are three areas where measured
gust values exceeded 80 mph: West central Illinois (IL), central Ohio (OH),
and northern Virginia (VA). However, there also exist other areas along the derecho
track where the maximum wind gusts were much weaker. Values below
severe limits (less than 58 mph) near the center of the derecho path were
observed in two areas: East central Illinois (IL)/west central Indiana (IN),
and eastern Ohio (OH) into southwest Pennsylvania (PA).

(2) Of
the 73 casualties associated with this derecho, Storm Data lists specific details
as to the cause of injury or death for 63, including the six deaths. The breakdown
includes:

The above
list highlights the greatest risks posed by derechos. Campers and boaters,
those outside generally, people in vehicles or mobile homes --- and even
those in buildings but near windows --- are the most vulnerable. Two of the deaths
and 19 of the injuries with the July 4-5, 1980 event were the result of falling
trees or tree limbs. Of those killed or injured in campgrounds, all were victims
during the night or early morning, when they were likely to have been sleeping.
The boating casualties all occurrred during the day, which is, of course,
when most recreational boaters are on the water.

A question
that might be asked is "Why is the 4-5 July 1980 derecho called the "More Trees Down' Derecho"?
This event was one of an unusually large number of derechos that affected
the Corn Belt during the summer of 1980. Similar to
1998, another year with many derechos in the Corn Belt,
a high pressure ridge dominated the central and southern Plains region
during summer, both at the surface and aloft. This pattern yielded extreme heat and
drought across the region. The
bow echo systems that produced the derechos occurred on the northern and
eastern fringe of the high pressure ridge, and they tended to move southeast
across the Corn Belt.

Robert
Johns, originator of the About Derechos page, was a forecaster with the NWS's
National Severe Storms Forecast Center (now the Storm Prediction Center) at
the time of the July 4-5 1980 event. He had a phone conversation with his father
shortly after the derecho had affected his parent's farm north of Indianapolis.
There was a small grove of large trees on the farm. His father mentioned that they
had experienced a series of severe windstorms during the past few weeks and that
they lost a tree or two with every windstorm that moved through. And with this
latest windstorm (July 4-5, 1980), there were now "more trees down" in the grove.
Johns' father was worried that there would not be any trees left standing by the end
of the summer. Hence, Johns dubbed the July 4-5, 1980 event the "More Trees Down"
derecho.